Various versions of such card webbers are known, e.g. from DE-OS 24 29 106. These devices serve to plait a card web in several layers on top of each other while forming a fleece. The card web is produced in an upstream carder and processed further in a machine following the webber, e.g. in a needle punching machine. In the needle punching machine the fleece is compressed and densified, thus creating a so-called needle felt.
In the card webber or in the machines preceding it or following it mistakes may occur during the processing for physical or mechanical reasons, which may result in inhomogeneities in the fleece or in the finished end product. Physical problems, e.g. occur in the card webber in which the card web is continuously moved over the conveyor belts while the two folding carriages execute a reversible movement over a limited section and in addition they have to slow down and then accelerate again at the reversal points of their paths. This results in material accumulation at the material edges. DE-OS 24 29 106 tries to solve this problem by means of complicated kinematics of the movement of the folding carriages relative to one another, connected with a synchronized controlling means of the webber. Herein an internal intermediate storage is formed via an auxiliary carriage which is filled and emptied to homogenize the folding movement. Due to the high effort and expenditure required for the construction of this device, however, it did not catch on in practice. It does not offer a solution for processing inhomogeneities and the influence of other machines.